The stench rolls off the sewage tanks and lingers in the hot, humid air over the Stonecrest and Longview neighborhoods.

Most of the time, Eric Roselle, who has lived on Hartford Road near the Columbia Regional Wastewater Treatment Plant for six years, doesn’t notice any odor at all.
But sometimes, usually on muggy summer days, the smell can become overwhelming.

“Once in a while, it’s really bad,” Roselle said. “It’s this strange odor in the air, nothing toxic. It’s not like an outhouse. It’s just strange.”

Annette Molitor, who for 11 years has lived on Gabrianna Court in one of the homes closest to the plant, said she can smell the odor almost all the time.

“We have a really nice deck and a really nice house, and we have a lot of different functions at our house,” Molitor said. “Every time you have a party, you think, ‘Oh my gosh, I hope the plant doesn’t smell.’ We worry every time we have a get-together.”

She said the family seldom even opens the home’s windows, fearing the smell will permeate the air.

Becky Awad lives farther away, down the hill on Cedar Rock Court.

“The month of July is when you can really pick it up, even where I live, and that’s quite a distance from the plant itself,” she said. “It just lingers.”

If voters pass a $77 million sewer bond issue on April 8, the city would spend $3 million of that money to add an additional odor control system, which Plant Superintendent Joel Gambill said would drastically curtail the odors.

The city already has some odor-reducing measures in place. Methane gas that is not used for energy within the plant is burned off. Fans across the plant’s ground blow an orange scent to mask the bad odors. Ferrous chloride is used in some tanks to reduce hydrogen sulfide, which produces a rotten egg smell. The plant is staffed 24 hours a day, 7 days a week, so if residents call to complain, someone will check to see if all the equipment is working properly.

“We try to be a good neighbor, but we’re getting sewage from 500 miles of sewer pipes across the city and dealing with 15 (million) to 20 million gallons of sewage per day,” Gambill said. “It can get really bad, especially when there’s a temperature inversion. It’s pretty harmless. It just smells bad.”

Another reason for the proposed odor control is that there are now more people living near the plant on Gillespie Bridge Road. Several new developments have popped up within the last 15 years, said Steve Hunt, the city’s environmental services manager. When the plant was built in 1983, there weren’t many homes close to the plant, he said.

The city plans to use bond money to add covers to the open sewage tanks and to install an air cleaning system that uses carbon “scrubbers” to remove odor-causing particles from the air.

Upgrades would also be made to the aeration tank, where oxygen is injected to help breed the microorganisms that break down the sewage. The tank’s aerators, which add oxygen through constant churning, would be replaced with fine bubble diffusers. The churning creates lots of splashing, which causes odor vapors to escape into the air. The new diffusers would provide the same amount of oxygen without much splashing.

But Gambill warned that if the bond issue fails and the city has to come up with other revenue to pay for the updates, the odor control system might have to be cut. Eliminating odors isn’t as high on the list of priorities as increasing plant reliability and meeting the new Missouri Department of Natural Resources limit on ammonia.

“We may not get everything we need,” Gambill said. “And the odor control would be the first thing to go.”

If the issue does pass, residents can expect a significant relief from the smells that drift into their neighborhoods, he said.

“It doesn’t mean we’re never going to have odors, but it will be a huge decrease,” he said.

That’s welcome respite for Molitor, who said a bad smell can put a damper on being in her own back yard. “We have a hot tub, too, and it’s just awful when you’re out enjoying the evening and the stars and all of a sudden there’s this odor from the plant,” she said.